Preservation of fungal samples

[Andreas Gminder]

-----Ursprüngliche Nachricht-----
Von: Heather Erika Hallen <hallenhe at PILOT.MSU.EDU>
An: TAXACOM at USOBI.ORG <TAXACOM at USOBI.ORG>
Datum: Donnerstag, 8. Juli 1999 21:07
Betreff: Preservation of fungal samples


>A query for anybody involved in fungal herbarium work:
>
>I normally airdry my samples (I deal solely with fleshy Basidiomycetes;
>Agaricales and Aphyllophorales), place them in herbarium boxes, stick them
in a
>cabinet, and they're fine. I noticed today that, in a box of Lepiota
americana
>which I thought I had dried thoroughly last year (samples had been left at
60
>degrees C for 18 hours; entire sample sample was rigid and dry to the
touch),
>the base of the stipe of each mushroom was rotting. Color had changed from
pink
>to brown, tissue was soft and moist to the touch. I have placed the samples
>back in the plant drier. If I cut off the affected parts of the fungi,
should
>that be enough to preserve the remainder of the sample? Would it help to
put a
>dessicant in with the things? Has anybody else had this problem?
>
>Much thanks for any suggestions.
>
>Heather Hallen



Dear Heather,
I have had the same problems you describe, but only in very few cases. The
funny thing is, that I still have not the slightest idea what caused these
few exsiccates to rehydrate again. Same as in your case they have been dried
thoroughly within appr. 24 hours and they were completely dry and easily
breaking. Several days later the content of the bag (I use plastic bags
which close air-tight) was quite ruined. I also have the case of a Russula
exsiccate which I have re-dried several times now in the last three years,
in some cases for two days. And it always gets soft again. Only weakly and
not really moist, but nevertheless. Please don't ask me why. I have even put
the open plastic bag on the drier to be certain that there should be no
moisture anymore. Great mystery ....

Normally it should be sufficient to put the specimen on the dryer again and
it will be okay after that. I think I would not even cut of the affected
parts if it is an important specimen. If it would be a rich collection and
of minor importance I would eliminate the destroyed fruitbodies or at least
the destroyed parts of them.

Since I had this problem the first time I always let the ready prepared
specimens rest for some days in my working room before they are included in
the collection. If it did not become moist again within some days, it will
not do later.

Best wishes from Stuttgart,
Andreas Gminder